long2ip — Converts an long integer address into a string in (IPv4) Internet standard dotted format
string long2ip ( string $proper_address )
The function long2ip() generates an Internet address in dotted format (i.e.: aaa.bbb.ccc.ddd) from the long integer representation
意思就是：用于将一个数字格式的IPv4地址转换成字符串格式(192.168.0.1)
而ip2long恰好与之相反
Converts an long integer address into a string in (IPv4) Internet standard dotted format
eg:
<?php
$ip = gethostbyname('www.csdn.net');
$num_ip = ip2long($ip);
echo $num_ip,'<br/>';
echo long2ip($num_ip);
?>
结果：
